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Elmer S, Reddy DS. Therapeutic Basis of Generic Substitution of Antiseizure Medications. J Pharmacol Exp Ther 2022; 381:188-196. [PMID: 35241634 PMCID: PMC9132097 DOI: 10.1124/jpet.121.000994] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 02/25/2022] [Indexed: 11/22/2022] Open
Abstract
More than thirty antiseizure medications (ASMs) are available for treating epilepsy. ASMs differ in their potency and efficacy in controlling seizures by acting on diverse targets in the brain, often with variable pharmacokinetics. Moreover, nearly 30% of people with epilepsy have drug-resistant or intractable seizures. Generic substitution of ASMs is a complex issue. It is thought that frequent generic substitution in people with epilepsy may cause problems because the U.S. Food and Drug Administration (FDA) rules allow too much variability across products. The standard bioequivalence range (80% to 125%) appears too broad for many ASMs, especially those exhibiting little separation between therapeutic and toxic levels. Hence, sub-therapeutic concentration may lead to therapeutic failure with seizure recurrence, which could be life threatening. A supra-therapeutic level could result in adverse effects or compliance issues. There are reported issues with generic substitutions of phenytoin, topiramate, levetiracetam, carbamazepine, and lamotrigine. There is discussion in the epilepsy community about additional guidelines, including designation of generic ASMs as Narrow Therapeutic Index (NTI) drugs and how patient education plays a role in generic substitution. Overall, based on the published evidence on specific generic ASMs, FDA bioequivalence standards are not the cause of problems with generic ASM substitution. Rather, it is imperative that physicians and pharmacists provide adequate patient education on what to expect when switching to generic ASMs, including changes in medication shape and color. Another suggestion would be to consider that all ASMs be considered for inclusion in NTI class to prevent the clinical outcome issues associated with generic ASM switching. SIGNIFICANCE STATEMENT: There are critical aspects to consider when switching from a brand name antiseizure medication (ASM) when a generic becomes available or switching between generics. Generic ASMs are interchanged with little consideration of differences in therapeutic equivalence and other clinical factors. This article describes key issues on generic substitution of ASMs and highlights critical pharmacotherapeutic issues associated with generic ASMs.
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Affiliation(s)
- Sarah Elmer
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University Health Science Center College of Medicine, Bryan, Texas
| | - Doodipala Samba Reddy
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University Health Science Center College of Medicine, Bryan, Texas
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Hernández-Mitre MP, Medellín-Garibay SE, Rodríguez-Leyva I, Rodríguez-Pinal CJ, Zarazúa S, Jung-Cook HH, Roberts JA, Romano-Moreno S, Milán-Segovia RDC. Population Pharmacokinetics and Dosing Recommendations of Levetiracetam in Adult and Elderly Patients With Epilepsy. J Pharm Sci 2020; 109:2070-2078. [PMID: 32113977 DOI: 10.1016/j.xphs.2020.02.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 02/19/2020] [Accepted: 02/21/2020] [Indexed: 12/27/2022]
Abstract
The objective was to develop and externally validate a population pharmacokinetic model of levetiracetam in adult and elderly patients with epilepsy, and to perform dosing simulations to propose individualized dosing regimens more likely to achieve therapeutic concentrations. This prospective study included 367 plasma samples from 107 patients receiving oral levetiracetam. Samples were analyzed by HPLC-UV. Pharmacokinetic data, as well as patient demographic, clinical characteristics, other drug therapy, and the use of innovator or generic products of levetiracetam, were collected. Population modeling was performed with NONMEM and included internal and external validations of the final model. Simulations were used to propose optimized dosing regimens. The pharmacokinetics of levetiracetam was described by a one-compartment model with first-order absorption and linear elimination. Body surface area had a significant effect on the apparent volume of distribution, as did creatinine clearance (CrCL) over the drug clearance (p < 0.01). The final model performed adequately during external validation testing. The final model showed a better predictive performance. Dosing simulations support 1000 mg 12-hourly dosing of levetiracetam for patients with CrCL ~60-75 mL/min with higher dose needed for higher values (1500 mg 12-hourly for CrCL ~93-111 mL/min). Dosing regimens should be personalized to the patient's CrCL to maximize the likelihood of therapeutic concentrations.
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Affiliation(s)
- María Patricia Hernández-Mitre
- Laboratorio de Biofarmacia y Farmacocinética, Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | - Susanna Edith Medellín-Garibay
- Laboratorio de Biofarmacia y Farmacocinética, Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | | | - Cristian Jazmín Rodríguez-Pinal
- Laboratorio de Biofarmacia y Farmacocinética, Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | - Sergio Zarazúa
- Laboratorio de Biofarmacia y Farmacocinética, Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | - Helgi Helene Jung-Cook
- Departamento de Farmacia, Facultad de Química, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Jason A Roberts
- University of Queensland Centre for Clinical Research, Faculty of Medicine & Centre for Translational Anti-Infective Pharmacodynamics, School of Pharmacy, The University of Queensland, Brisbane, Australia; Departments of Pharmacy and Intensive Care Medicine, Royal Brisbane and Women's Hospital, Brisbane, Australia; Division of Anaesthesiology Critical Care Emergency and Pain Medicine, Nîmes University Hospital, University of Montpellier, Nîmes, France
| | - Silvia Romano-Moreno
- Laboratorio de Biofarmacia y Farmacocinética, Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | - Rosa Del Carmen Milán-Segovia
- Laboratorio de Biofarmacia y Farmacocinética, Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México.
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Atif M, Azeem M, Sarwar MR. Potential problems and recommendations regarding substitution of generic antiepileptic drugs: a systematic review of literature. SPRINGERPLUS 2016; 5:182. [PMID: 27026878 PMCID: PMC4766158 DOI: 10.1186/s40064-016-1824-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 02/15/2016] [Indexed: 12/22/2022]
Abstract
Despite the availability of generic antiepileptic drugs (AEDs), still patients and neurologists hesitate to make a switch due to assorted reasons. The objectives of this review were to evaluate the risks associated with the generic substitution of AEDs. In this context, we also summarized the recommendations of various international societies to treat epileptic patients. We used a number of electronic databases to identify the relevant published studies which demonstrated the potential problems and recommendations regarding generic substitution of AEDs. Of 204 articles found initially, 153 were selected for additional review. Subsequently, 68 articles were finally selected. This review concluded that potential problems linked with the generic substitution of AEDs could be bioequivalence issues, failure of drug therapy, emergence of adverse events and increase in the frequency of seizures. The reasons could be the pharmacokinetics properties of AEDs and unique characteristics of some epilepsy patients. Consequently, the generic substitution of AEDs affects the successful treatment and quality of life of the patients. Various guidelines recommend the well-controlled epileptic patients to avoid switching from brand-to-generic products, generic-to-brand products or generic to some other generic products.
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Affiliation(s)
- Muhammad Atif
- Department of Pharmacy, Faculty of Pharmacy and Alternative Medicine, The Islamia University of Bahawalpur, Bahawalpur, Punjab Pakistan
| | - Muhammad Azeem
- Department of Pharmacy, Faculty of Pharmacy and Alternative Medicine, The Islamia University of Bahawalpur, Bahawalpur, Punjab Pakistan
| | - Muhammad Rehan Sarwar
- Department of Pharmacy, Faculty of Pharmacy and Alternative Medicine, The Islamia University of Bahawalpur, Bahawalpur, Punjab Pakistan
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Borg JJ, Tomasi P, Pani L, Aislaitner G, Pirozynski M, Leufkens H, Melchiorri D. Licensing of Generic Medicines: Are There Any Challenges Left? A Pharmaceutical Regulatory Perspective. Sci Pharm 2014; 82:847-56. [PMID: 26171329 PMCID: PMC4475802 DOI: 10.3797/scipharm.1312-10] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Accepted: 05/22/2014] [Indexed: 11/22/2022] Open
Abstract
When an innovative product (innovator) is not covered anymore by intellectual property rights, cheaper equivalent medicinal products (generic products) may be marketed and used in clinical practice. The regulation of generic products is well-established, and is primarily based on standard rules for quality, therapeutic equivalence requirements (the latter in most instances proven through a bioequivalence study), and safety data for the innovator. The extensive experience from bringing generic products to the market over the last decades allows the conclusion that they are well-accepted and provide a useful alternative option for cost-effective pharmacotherapy. While supporting this conclusion, there are a number of issues to be considered during the assessment of a generic product application. Six scenarios are described in total, from an efficacy and a safety perspective, where potential concerns with the current regulatory standards could arise in the approval of generic products. We also propose solutions to these scenarios in order to foster debate on these issues.
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Affiliation(s)
- John Joseph Borg
- Medicines Authority, 203 Level 3, Rue D’Argens, Gzira, GZR 1368, Malta
- Department of Biology, School of Pharmacy, University of Tor Vergata, Rome, Italy
| | - Paolo Tomasi
- European Medicines Agency, 7 Westferry Circus, London E14 4HB, UK
| | - Luca Pani
- Italian Medicines Agency, AIFA, Via del Tritone, 181, 00186 Rome, Italy
| | - George Aislaitner
- National Organisation of Medicines (EOF), 284 Messogion STF, 155 62 Athens, Greece
| | - Michal Pirozynski
- Department of Anaesthesiology and Critical Care Medicine, Postgraduate MedicalSchool, Czerniakowska 231, 00 416 Warsaw, Poland
| | - Hubert Leufkens
- Medicines Evaluation Board (MEB), Graadt van Roggenweg 500, 3531 AH Utrecht, Netherlands
| | - Daniela Melchiorri
- Department of Physiology and Pharmacology, University of Rome “Sapienza”, Rome, Italy
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Comparative plasma exposure and lung distribution of two human use commercial azithromycin formulations assessed in murine model: a preclinical study. BIOMED RESEARCH INTERNATIONAL 2013; 2013:392010. [PMID: 24073402 PMCID: PMC3773390 DOI: 10.1155/2013/392010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 07/03/2013] [Accepted: 07/24/2013] [Indexed: 12/02/2022]
Abstract
Azithromycin (AZM) therapeutic failure and relapses of patients treated with generic formulations have been observed in clinical practice. The main goal of this research was to compare in a preclinical study the serum exposure and lung tissue concentration of two commercial formulations AZM-based in murine model. The current study involved 264 healthy Balb-C. Mice were divided into two groups (n = 44): animals of Group A (reference formulation -R-) were orally treated with AZM suspension at 10 mg/kg of b.w. Experimental animals of Group B (generic formulation -G-) received identical treatment than Group A with a generic formulation AZM-based. The study was repeated twice as Phase II and III. Serum and lung tissue samples were taken 24 h post treatment. Validated microbiological assay was used to determine the serum pharmacokinetic and lung distribution of AZM. After the pharmacokinetic analysis was observed, a similar serum exposure for both formulations of AZM assayed. In contrast, statistical differences (P < 0.001) were obtained after comparing the concentrations of both formulations in lung tissue, being the values obtained for AUC and Cmax (AZM-R-) +1586 and 122%, respectively, than those obtained for AZM-G- in lung. These differences may indicate large differences on the distribution process of both formulations, which may explain the lack of efficacy/therapeutic failure observed on clinical practice.
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Vercueil L. Brain tumor epilepsy: A reappraisal and six remaining issues to be debated. Rev Neurol (Paris) 2011; 167:751-61. [PMID: 21890158 DOI: 10.1016/j.neurol.2011.08.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Accepted: 08/08/2011] [Indexed: 12/28/2022]
Affiliation(s)
- L Vercueil
- INSERM U836, EFSN, Psychiatry and Neurology Pole, Grenoble Institut of Neurosciences, CHU Grenoble, Grenoble cedex 9, France.
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Abstract
In this issue Gagne et al. report an elegant case-crossover study of seizures in patients on antiepileptic drugs. They found that a dispensation episode approximately triples the risk of having a seizure within 21 days, but the risk is not statistically different whether the dispensation was of the same brand-name or generic drug as previously used or a switch from brand-name to a generic or from a generic to a brand name. The cause of the seizure might be a delay in taking medication or late redispensation, among others, but apparently the nature of the product dispensed is not relevant in this study; this may alleviate some of the concerns about generic drugs and epilepsy.
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